Fall 2017 Polling Bulletin: Iran

Analysis of polls released between September 24 and October 17, 2017
Peace & Security — Iran and the Nuclear Deal

The Top Line 

  • Half of the public supports the Iran deal. Eight polls found an average of 50% support for the JCPOA. Support has steadily increased since the start of the deal.
  • Many do not know the meaning of decertification. Thirty-nine percent have no knowledge/opinion on decertification, and 24% are undecided on withdrawal.
  • Public perceptions of Iran have thawed slightly since the deal. 30% view Iran as a “very serious” threat, a 19-point decline since the JCPOA was signed (2015).
  • But Iran is still seen as a threat, with 69% saying Iran is a serious threat, 76% an enemy or unfriendly.

Support for the Iran Deal

Despite an unfriendly attitude toward Iran, Americans have an appetite for diplomacy, and support for the Iran deal has risen over time.

Eight recent polls found an average of 50% support for the deal. CNN/SRSS finds 67% support, the Chicago Council 60%, CBS/YouGov 58%, Economist/YouGov 56%, Morning Consult 54%, Harvard/Harris 40%, NBC/SurveyMonkey 39%, and Quinnipiac 31%.

There are a few factors that contribute to the 36-point range across polls. Polling questions including less information about the Iran deal tend to find less support for it. The most recent batch of polls illustrates this phenomenon: the polls on the lower end of the gap—Harvard/Harris, NBC/SurveyMonkey, and Quinnipiac—do not explain what the Iran deal is.

In addition, NBC/SurveyMonkey’s sample population skews older than the other polls with available demographic information; since older generations tend to be more conservative, this may help explain the poll’s lower support finding. (Harvard/HarrisNBC/SurveyMonkeyQuinnipiac).

By contrast, CNN/SRSS tracks relatively high. Their question explains the Iran deal, but does not mention US concessions in the deal, which may contribute to an upward bias. (CNN/SRSS).

The issue remains highly partisan. Liberals are almost twice as likely as Conservatives to “strongly” support the Iran deal in the Economist/YouGov poll (48–26%). Likewise, while three quarters (73%) of Democrats in the Chicago Council poll favor participation in the Iran deal, just half of Republicans agree (48%). (Economist/YouGovChicago Council).

Summary: A majority of Americans support the Iran deal, with Liberals/Democrats supporting the deal more than Conservatives/Republicans. Wide variation across polls is likely due to the amount of information provided.


While a plurality (44%) believe presidents “need to follow” the treaties of their predecessors and a majority support the Iran deal, according to Economist/YouGov, the public appears unsure about decertification. Suffolk/USA Today finds that the public is split 38–37% on withdrawing from the deal. Morning Consult finds a similar split, 37–34%, on recertification. Harvard/Harris finds a 66­–34% split in favor of renegotiating the deal, a 68–32% split in favor of decertification and imposing sanctions, and a 51–49% split in favor of President Trump’s decision to decertify the deal. (Economist/YouGovSuffolk/USA TodayMorning ConsultHarvard/Harris).

Public uncertainty may have to do with a weak understanding of “certification,” which the polling questions do not define well. Morning Consult does not define re/decertification at all. Suffolk/USA Today and Harvard/Harris define withdrawal/decertification as putting the Iran deal in Congress’ hands without mentioning its uncertain fate there. Harvard/Harris question on renegotiation furthermore suggests that Iran is not living up to its end of the bargain. This highly leading question precedes the one on decertification, casting doubt on its findings. (Morning ConsultHarvard/Harris).

Suffolk/USA Today and Morning Consult also demonstrate a substantial knowledge gap—39% in Morning Consult have no knowledge or opinion, and 24% in Suffolk/USA Today are undecided on the issue. (Suffolk/USA TodayMorning Consult). These are high percentages of people self-reporting a lack of knowledge or opinion: respondents typically under-report the degree to which they don’t understand an issue.

This knowledge gap provides an opportunity for advocates to define what decertification is and what it would mean for the deal.

Summary: Despite support for commitment to pre-existing international treaties and majority support for the Iran deal, the public appears divided on withdrawal/decertification. A large proportion expresses no opinion, not enough information, or indecision, which points to weak public understanding of certification. This provides an opportunity for advocates to define re/decertification in public facing communications.

Iran as a Threat

A recent CNN/SRSS poll suggests that a strong majority of Americans (69%) consider Iran a serious threat. Only 30%, however, consider Iran a “very serious threat,” a 19-point decline since the start of the Iran deal.

Recent Morning Consult data also suggests that only 2% of registered voters consider Iran the “greatest threat” to US national security, with far more considering North Korea the greatest threat (50%), followed by ISIS (18%), Russia (14%), and China (6%). Likewise, only 4% consider Iran the “greatest immediate threat” in a recent NBC/SurveyMonkey poll. (CNN/SRSSMorning ConsultNBC/SurveyMonkey).

A 44% plurality in the Economist/YouGov poll nonetheless view Iran as an enemy of the United States, and 32% as unfriendly. NBC/SurveyMonkey finds a similar overall proportion, but in reverse—33% consider Iran an enemy and 48% unfriendly. (Economist/YouGovNBC/SurveyMonkey).

Americans have considered Iran an enemy, or a threat, or unfriendly for decades. This opinion is deeply entrenched and unlikely to reverse in the short term.

Summary: While a majority continues to view Iran as a threat, that threat has downgraded slightly since the 2015 Iran deal, and the public does not consider Iran a primary threat to the United States. However, over three quarters continue to view Iran as an enemy and unfriendly, maintaining a decades-long trend.

Date Released

Nov 1, 2017